This disclosure relates to a system and method for treating a subterranean well formation to stimulate the production of hydrocarbons and, more particularly, such an apparatus and method for fracturing the well formation.
Several techniques have evolved for treating a subterranean well formation to stimulate hydrocarbon production. For example, hydraulic fracturing methods have often been used according to which a portion of a formation to be stimulated is isolated using conventional packers, or the like, and a stimulation fluid containing gels, acids, sand slurry, and the like, is pumped through the well bore into the isolated portion of the formation. The pressurized stimulation fluid pushes against the formation at a very high force to establish and extend cracks on the formation. However, the requirement for isolating the formation with packers is time consuming and considerably adds to the cost of the system.
One of the problems often encountered in hydraulic fracturing is fluid loss which for the purposes of this application is defined as the loss of the stimulation fluid into the porous formation or into the natural fractures existing in the formation.
Fluid loss can be reduced using many ways, such as by using foams. Since foams are good for leak off prevention, they also help in creating large fractures. Conventionally, foaming equipment is provided on the ground surface that creates a foam, which is then pumped downhole. Foams, however, have much larger friction coefficients and reduced hydrostatic effects, both of which severely increase the required pressures to treat the well.
Therefore, what is needed is a stimulation treatment according to which the need for isolation packers is eliminated, the foam generation is performed in-situ downhole, and the fracture length is improved.
According to an embodiment of the present invention, the techniques of fracturing, isolation and foam generation are combined to produce an improved stimulation of the formation. To this end, a stimulation fluid is discharged through a workstring and into a wellbore at a relatively high impact pressure and velocity without the need for isolation packers to fracture the formation.